Saturday, 8 December 2012

Some Sun, Some Trees, Some Cloud - 8th December

The title of this post sums up solar observing for me in winter:  I'd borrowed a PST on the grounds it's nice and portable and on a camera tripod could capitalise on the the moments when the sun is inbetween the gaps in the trees...

Putting on one of the external etalons from my DS40 I started observing visually and was pleased with the results the DS PST gave me.  I soon became aware that the clouds were rolling in fast on the still northerly breeze and so turned my attentions to trying to get some images.   First off I tried the DMK31 but this does not give a full disk in the fov, and was clear that that etalon in the PST was rather 'slack and sloppy' and was difficult to get the sweet spot centralised in the fov.  As a result features on the disk went in and out of band as the sun drifted through the fov.  Needless to say this PST will be getting a 'hypertune' to improve matters.

Time to switch to the Opticstar PL130M, as mentioned in the previous posting i've been trying to get this working better for solar work; today reminded me of something i'd found previouslly with this camera - it's not possible to set the exposure short enough; it was only when the haze got thicker I was able to stop the histogram from clipping.  I have a ND filter I will incorporate next time I get to image with it.  The fact the image is undersampled in firecapture to 640x480 when recording is a real hindrance - so much detail is being lost.  I'm hoping with time this is something the author of the software might address.  It took some considerable time using the variable settings that were available to come up with something that rendered some of the disk detail visible, and even then it's nowhere near the quality of the DMK.  Dropping the gamma setting on the opticstar definitely seems to have the effect of reducing the dynamic range it is recording.  I may have to try messaging them and see if there is any alternative control software available to improve matters.

Still, given the conditions and variables that have conspired, i'm pretty pleased with the result!